Hydrochlorothiazide, a classic among antihypertensive drugs, has recently been thrust into the limelight again due to the doping incident. Current events aside, let’s take a look at this hydrochlorothiazide from a medical perspective. Hydrochlorothiazide is one of the antihypertensive drugs and one of the drugs used to treat heart failure. Diuretics are still a big part of the antihypertensive team in the “Guidelines for the Rational Use of Hypertension” issued by the National Health Planning Commission. Diuretics have been used for antihypertensive treatment for more than half a century. The advantage of these drugs is that they can control refractory hypertension and can significantly reduce the incidence of cardiovascular events and mortality. Despite its long history, a large part of the population still relies on them to lower blood pressure in the vast rural areas of China because of their low price and precise antihypertensive effect. Hydrochlorothiazide is one of the diuretics, and its principle of lowering blood pressure is diuretic by draining sodium and potassium, excreting the excess water inside our body in the form of urine through the kidneys. 55% of blood is plasma, and 90% of plasma is water. Diuretics reduce the blood volume in blood vessels by draining excess water out of blood vessels, and the pressure of blood on the side walls of blood vessels decreases, which in turn reduces the pressure on cardiovascular vessels and reduces the risk of cardiovascular diseases. Just like the water in the river, in the flood season, the river is soaring, forming a huge pressure on the river bank, we pump out the excess water through the pumping machine, the amount of water in the river is reduced, the pressure on the river bank will be reduced, and the risk of the river breaking the bank will be reduced. The action of hydrochlorothiazide is equivalent to a water pumping machine, so it has been regarded as a classic by cardiologists for its exact effect of lowering blood pressure. Hydrochlorothiazide is indicated for the initial and maintenance treatment of most patients with hypertension, and is particularly suitable for the treatment of heart failure combined with hypertension and salt-sensitive hypertension. Diuretics in patients with heart failure can reduce blood volume, reduce the load on the heart, improve the symptoms of heart failure, and also reduce the edema of the lower extremities due to heart failure. The high sodium intake of people with high salt diet causes the blood sodium level to increase, and due to the effect of osmotic pressure, the water between the tissues will flow to the blood vessels, resulting in the increase of blood volume and blood pressure. However, hydrochlorothiazide is prohibited for patients with gout, and people who do not have gout but have increased blood uric acid should also use hydrochlorothiazide with caution. Hydrochlorothiazide is banned in sports because it appears to the Olympic Committee to reduce the weight of athletes or to speed up the excretion of other banned substances to avoid anti-doping detection, creating an unfair situation in competition. As doctors, we are more concerned about its effects on the bodies of Olympic athletes. In sports competitions, athletes sweat like rain and are physically exhausted, they are already prone to electrolyte disorders, resulting in heat stroke and dehydration, etc. If they take hydrochlorothiazide, its sodium excretion will aggravate the electrolyte disorders, which can lead to dehydration shock or even death in serious cases. So for their own health, athletes should not take such drugs either. In fact, the spirit of sports is to enhance physical fitness, and the rules of competition make us forget what the original meaning of sports is. The best interpretation of sportsmanship is to focus on participation and to stay healthy. Whether there is a gold medal or not doesn’t matter, getting healthy through sports should be our common goal.